Polymeric amine synergists

ABSTRACT

The present disclosure is drawn to polymeric amine synergists, photo curable inks containing the polymeric amine synergists, and methods of making the photo curable inks. A polymeric amine synergist can include an aminobenzene modified with a polyether chain connecting to the aminobenzene through an amide linkage.

BACKGROUND

Recently, curing of ink by radiation, and in particular ultraviolet (UV)curing, has become popular. UV curable ink can be cured after printingby application of UV light. Typically, UV curable inks include monomersthat form polymers by free radical polymerization. The growing end ofeach polymer chain is a radical that reacts with additional monomers,transferring the radical to the end of the chain as each monomer isadded. A photo initiator is used to form the first radicals to begin thepolymerization process. The photo initiator is capable of absorbing UVlight to generate radicals to react with the monomers.

Two types of photo initiators can be used in UV curable compositions.Type I photo initiators are unimolecular photo initiators that undergo ahemolytic bond cleavage upon absorption of UV light, forming radicals.Type-II photo initiators are bimolecular photo initiators. These areused as a system of a photo initiator with a synergist, which cantogether form radicals upon exposure to UV light. Some type-II photoinitiators react by hydrogen abstraction from the synergist to the photoinitiator.

DETAILED DESCRIPTION

The present disclosure is drawn to polymeric amine synergists. Morespecifically, the present disclosure provides polymeric amine synergistsincluding an aminobenzene modified with a polyether chain connecting tothe aminobenzene through an amide linkage. The polymeric aminesynergists can be water soluble and stable in aqueous inks, such asaqueous thermal inkjet ink. The polymeric amine synergists also resistmigration in the ink after curing. Thus, the polymeric amine synergistsof the present disclosure overcome some of the drawbacks of othersynergists. Some small molecular weight synergists, such asmethyldiethanolamine, trimethylamine, and its analogs, can have unwantedodor, toxicity, and migration in cured materials.

The inkjet printing industry uses various types of inks, such asoil-based inks, solvent-based (non-aqueous) inks, water-based (aqueous)inks, and solid inks which are melted in preparation for dispensing.Solvent-based inks are fast drying, and as a result, are widely used forindustrial printing. When solvent-based inks containing binders andother ingredients are jetted onto a substrate, the solvent(s) partiallyor fully evaporate from the ink, leaving the binder and otheringredients such as pigment particles on the printed substrate in theform of a dry film. During the drying process, the solvents, which areoften volatile organic compounds (VOC), emit vapors, and therefore, canpollute the environment. The amount of pollution produced can increasegreatly with higher printing speeds or for wide format images, wherelarge amounts of ink are deposited onto a substrate. As a result of thisand other concerns, efforts related to preparing inks that areenvironmentally friendly have moved some research in the direction ofwater-based inks. However, radiation-curable (or photo-curable)water-based ink compositions are noticeably limited among availableoptions due to their specific formulation properties. Accordingly, thedevelopment of radiation-curable water-based inks, otherwise referred toas photo curable inks, that exhibit specific desirable printingproperties such as, for example, jetting properties as well as improvedadhesion, would be an advancement in the field of inkjet technology.

Accordingly, a polymeric amine synergist can include an aminobenzenemodified with a polyether chain connecting to the aminobenzene throughan amide linkage. As used herein, “aminobenzene” refers to the compoundalso referred to as aniline or phenylamine, as well as analogs of thiscompound with attached R-groups, such as dimethylaniline. The aminogroup of the aminobenze can be a primary amine, secondary amine, ortertiary amine.

The polyether chain can be a polyglycol, paraformaldehyde, or otherpolyether. For example, the polyether chain can be polyethylene glycol(PEG), methoxypolyethylene glycol (MPEG), polypropylene glycol (PPG),polybutylene glycol (PBG), or a polyglycol copolymer. In one specificexample, the polyether chain can be selected from polyethylene glycol,polypropylene glycol, and a copolymer of polyethylene glycol andpolypropylene glycol. In another specific example, the polyether chaincan be derived from a portion of a commercially available polyetheramine such as Jeffamine® ED-900, Jeffamine® M-1000 (both available fromHuntsman Corporation), or others. Various molecular weights of polyethercan be suitable. The type of polyether chain and the molecular weight ofthe polyether chain can in some cases affect the solubility of the finalpolymeric amine synergist. For example, a higher ratio of oxygen atomsto carbon atoms in the polyether chain tends to make the polymeric aminesynergist more soluble. The molecular weight of the polyether chain canalso affect the degree to which the polymeric amine synergist canmigrate in a cured ink. Longer polyether chains can make it moredifficult for the polymeric amine synergist to move within a cured ink,thus decreasing migration. Therefore, the type of polyether chain can beselected to give good water solubility and low migration of thepolymeric amine synergist in cured ink. In one example, the polyetherchain can be a polyglycol having at least 5 glycol monomer units.

The polyether chain can connect to the aminobenzene through an amidelinkage. As used herein, “amide linkage” refers to either an amide groupor an amide group with a bridging group attached to the carbon atom ofthe amide group. Further, as used herein, connecting the polyether chainto the aminobenzene through an amide linkage means that the polyetherchain is directly bonded to the nitrogen atom of the amide group, andthe carbon atom of the amide group is either directly bonded or linkedthrough the bridging group to a carbon atom in the aromatic ring of theaminobenzene. This amide linkage can be formed by a suitable reaction,such as a substitution reaction or a condensation reaction.

The aminobenzene, polyether chain, and amide linkage do not necessarilymake up the entire polymeric amine synergist. For example, additionalgroups can be attached along the polyether chain or at the opposite endof the polyether chain. In some cases, one or more additionalaminobenzene moieties can be attached to the polyether chain. Theseadditional aminobenzene moieties can connect to the polyether chainthrough amide linkages. In one example, an additional aminobenzenemoiety can connect to an opposite end of the polyether chain through anamide linkage. In other examples, the polyether chain can have multiplebranches and each branch can terminate with an aminobenzene moietyconnected to the polyether chain through an amide linkage. Specificexamples of such polymeric amine synergists are described in detailbelow.

In some examples, the aminobenzene with the amide linkage can have ageneral formula according to Formula 1:

In Formula 1, the amide linkage is illustrated as an amide group with abridging group Y bonded to the aromatic ring of the aminobenzene. Theamide linkage can be bonded to any of the available carbon atoms in thering by replacing a hydrogen atom. The groups R₁, R₂, and R₃ can beindependently a hydrogen atom, an unsubstituted alkyl, a substitutedalkyl, an unsubstituted alkenyl, a substituted alkenyl, an unsubstitutedaryl, a substituted aryl, an unsubstituted aralkyl, a substitutedaralkyl, a halogen atom, —NO₂, —O—R_(d), —CO—R_(d), —CO—O—R_(d),—O—CO—R_(d), —CO—NR_(d)R_(e), —NR_(d)R_(e), —NR_(d)—CO—R_(e),—NR_(d)—CO—O—R_(e), —NR_(d)—CO—NR_(e)R_(f), —SR_(d), —SO—R_(d),—SO₂—R_(d), —SO₂—O—R_(d), —SO₂NR_(d)R_(e), or a perfluoroalkyl group,wherein R_(d), R_(e), and R_(f) are independently a hydrogen atom, anunsubstituted alkyl, a substituted alkyl, an unsubstituted alkenyl, asubstituted alkenyl, an unsubstituted aryl, a substituted aryl, anunsubstituted aralkyl, or a substituted aralkyl. In one specificexample, R₁ to R₃ can each be a hydrogen atom. The Y group can be abond, (CH₂)_(q), or O(CH₂)_(q), wherein q is any integer from 1 to 100.Formula 1 illustrates only the aminobenzene with the amide linkage. Acomplete polymeric amine synergist can be formed by combining anaminobenzene and amide linkage as in Formula 1 with a polyether chain.The polyether chain can be bonded to the nitrogen atom in the amidelinkage.

In some examples, the polymeric amine synergist can have a generalformula according one of Formulas 2-5:

In each of Formulas 2-5, the groups R₁, R₂, R₃, and R₄ can beindependently a hydrogen atom, an unsubstituted alkyl, a substitutedalkyl, an unsubstituted alkenyl, a substituted alkenyl, an unsubstitutedaryl, a substituted aryl, an unsubstituted aralkyl, a substitutedaralkyl, a halogen atom, —NO₂, —O—R_(d), —CO—R_(d), —CO—O—R_(d),—O—CO—R_(d), —CO—NR_(d)R_(e), —NR_(d)R_(e), —NR_(d)—CO—R_(e),—NR_(d)—CO—O—R_(e), —NR_(d)—CO—NR_(e)R_(f), —SR_(d), —SO—R_(d),—SO₂—R_(d), —SO₂—O—R_(d), —SO₂NR_(d)R_(e), or a perfluoroalkyl group. Inthese examples, R_(d), R_(e), and R_(f) are independently a hydrogenatom, an unsubstituted alkyl, a substituted alkyl, an unsubstitutedalkenyl, a substituted alkenyl, an unsubstituted aryl, a substitutedaryl, an unsubstituted aralkyl, or a substituted aralkyl. In onespecific example, R₁ to R₄ can each be a hydrogen atom. The numbers ofmonomer units m, n, and p can be independently any integer from 0 to200, provided that the sum of m, n, and p is at least 5. The Y group canbe a bond, (CH₂)_(q), or O(CH₂)_(q), wherein q is any integer from 1 to100.

As shown in Formulas 2-5, the polymeric amine synergist can include 1,2, 3, or 4 aminobenzene moieties connected to a branching polyetherchain. In other examples, the polyether chain can have more than 4branches terminating in aminobenzene moieties.

In one example, the polymeric amine synergist can have a general formulaaccording to Formula 6:

In the specific example described by Formula 6, m, n, and p can be anyinteger provided that the sum of m, n, and p is from 10 to 25.

The molecular weight of the polymeric amine synergist can affect itsdegree of migration in cured ink. For example, a polymeric aminesynergist with a weight average molecular weight (Mw) of about 500 Mw ormore can have reduced migration in cured ink compared with a smallmolecule synergist. Migration can be further reduced by increasing themolecular weight of the polymeric amine synergist to about 1000 Mw ormore. In one example, the polymeric amine synergist can have a molecularweight from about 500 Mw to about 5000 Mw. Polyethers of variousmolecular weights are available, allowing for the production ofpolymeric amine synergist with various molecular weights. In someexamples, the polyether chain can be selected from PEG 550, PEG 600, andPEG 1000. In another specific example, the polyether chain can bederived from the polyethyleneoxy polypropyleneoxy chain portion of acommercially available polyether amine such as Jeffamine® ED-900,Jeffamine® M-1000 (both available from Huntsman Corporation), or others.In polymeric amine synergists having multiple aminobenzene moieties, asmaller molecular weight polyether chain can be used while stillmaintaining a high overall molecular weight of the polymeric aminesynergist. The molecular weight of the polymeric amine synergist canalso be changed by adding R groups to the aminobenzene. It is noted thatwhen referring to “R groups” generically herein, this term is defined toinclude at least H and organic side chain side groups and other specificconstituents described and defined elsewhere herein, e.g., R, R₁, R₂,R₃, R₄, R₅, R₆, R_(d), R_(e), R_(f), etc.

The molecular weight of the polymeric amine synergist can also affectits solubility in water. In some cases, the polyether chain can be awater soluble polyether. Although the aminobenzene alone can beinsoluble in water, adding the soluble polyether chain can make theentire polymeric amine synergist soluble. In such cases, the solublepolyether can have a sufficient molecular weight so that its solubilityproperties overcome the insolubility of the aminobenzene. In othercases, water soluble R groups can be added to the aminobenzene toincrease the solubility of the polymeric amine synergist. In oneexample, the polymeric amine synergist can have a water solubility of atleast 0.5 wt %.

Typical aqueous ink jet inks can have a pH in the range of 7 to 12. Somecommercially available synergists with ester linkages can break down insuch basic conditions. The amide linkage in the polymeric aminesynergists according to the present disclosure can be stable under theseconditions. In some examples, the polymeric amine synergist can bestable in water up to a pH from 7 to 12. In other examples, thepolymeric amine synergist can be stable in water up to a pH of 8 orhigher. As used herein, “stable” refers to the ability of the polymericamine synergist to have a shelf life of at least 1 year. Typically,aqueous ink jet inks can have a shelf life of greater than 1 year,greater than 2 years, or longer.

A general pathway for forming a polymeric amine synergist in accordancewith an example of the present disclosure is shown in Formula 7:

In the pathway shown in Formula 7, R₁ to R₄ each independently representa hydrogen atom, a substituted or unsubstituted alkyl, alkenyl, aryl oraralkyl group or a group selected from a halogen atom, —NO₂, —O—R_(d),—CO—R_(d), —CO—O—R_(d), —O—CO—R_(d), —CO—NR_(d)R_(e), —NR_(d)R_(e),—NR_(d)—CO—R_(e), —NR_(d)—CO—O—R_(e), —NR_(d)—CO—NR_(e)R_(f), —SR_(d),—SO—R_(d), —SO₂—O—R_(d), —SO₂NR_(d)R_(e) or a perfluoroalkyl group.R_(d), R_(e) and R_(f) independently represent a hydrogen or asubstituted or unsubstituted alkyl, alkenyl, aryl or aralkyl group. Thenumbers of monomer units m and n can be any integer from 0 to 200,provided that the sum of m and n is at least 5. The Y group can be abond, (CH₂)_(q), or O(CH₂)_(q), wherein q is any integer from 1 to 100.

According to this pathway, an aniline acid (1) is reacted with thionylchloride to give a corresponding acid chloride (2). The acid chloride(2) is treated with a mono-substituted polyethyleneoxy polypropyleneoxyamine (3) giving the desired polymeric amine synergist. Lines leading tothe center of aromatic rings in the aniline acid (1), acid chloride (2),and the final polymeric amine synergist signify that the group can beattached at any available location on the ring.

An alternate example of a general pathway for forming a polymeric aminesynergist in accordance with the present disclosure is shown in Formula8:

In the pathway shown in Formula 8, R₁ to R₃ each independently representa hydrogen atom, a substituted or unsubstituted alkyl, alkenyl, aryl oraralkyl group or a group selected from a halogen atom, —NO₂, —O—R_(d),—CO—R_(d), —CO—O—R_(d), —O—CO—R_(d), —CO—NR_(d)R_(e), —NR_(d)R_(e),—NR_(d)—CO—R_(e), —NR_(d)—CO—O—R_(e), —NR_(d)—CO—NR_(e)R_(f), —SR_(d),—SO—R_(d), —SO₂—R_(d), —SO₂—O—R_(d), —SO₂NR_(d)R_(e) or a perfluoroalkylgroup. R_(d), R_(e) and R_(f) independently represent a hydrogen or asubstituted or unsubstituted alkyl, alkenyl, aryl or aralkyl group. Thenumbers of monomer units m, n, and p can be any integer from 0 to 200,provided that the sum of m, n, and p is at least 5. The Y group can be abond, (CH₂)_(q), or O(CH₂)_(q), wherein q is any integer from 1 to 100.

According to this pathway, an aniline acid (1) is reacted with thionylchloride to give a corresponding acid chloride (2). The acid chloride(2) is treated with a polyethyleneoxy polypropyleneoxy diamine to givethe desired polymeric amine synergist having two aniline moieties. Linesleading to the center of aromatic rings in the aniline acid (1), theacid chloride (2), and the final polymeric amine synergist signify thatthe group can be attached at any available location on the ring.

A further example of a general pathway for forming a polymeric aminesynergist in accordance with the present disclosure is shown in Formula9:

In the pathway shown in Formula 9, R₁ to R₄ each independently representa hydrogen atom, a substituted or unsubstituted alkyl, alkenyl, aryl oraralkyl group or a group selected from a halogen atom, —NO₂, —O—R_(d),—CO—R_(d), —CO—O—R_(d), —O—CO—R_(d), —CO—NR_(d)R_(e), —NR_(d)R_(e),—NR_(d)—CO—R_(e), —NR_(d)—CO—O—R_(e), —NR_(d)—CO—NR_(e)R_(f), —SR_(d),—SO—R_(d), —SO₂—O—R_(d), —SO₂—O—R_(d), —SO₂NR_(d)R_(e) or aperfluoroalkyl group. R_(d), R_(e) and R_(f) independently represent ahydrogen or a substituted or unsubstituted alkyl, alkenyl, aryl oraralkyl group. The numbers of monomer units n can be any integer from 5to 200. The Y group can be a bond, (CH₂)_(q), or O(CH₂)_(q), wherein qis any integer from 1 to 100.

According to this pathway, a glycerol polyethylene glycol derivative (5)is reacted with toluenesulfonyl chloride to give a correspondingtosylate (6). The tosylate (6) is treated with sodium azide to give thecorresponding azide (7). Then, the azide (7) is hydrogenated to give atriamine (8). This triamine (8) reacts with an aniline acid chloride (2)to give the desired polymeric amine synergist having three anilinemoieties. Lines leading to the center of aromatic rings in the anilineacid (1), aniline acid chloride (2), and the final polymeric aminesynergist signify that the group can be attached at any availablelocation on the ring.

Yet another example of a general pathway for forming a polymeric aminesynergist in accordance with the present disclosure is shown in Formula10:

In the pathway shown in Formula 10, R₁ to R₃ each independentlyrepresent a hydrogen atom, a substituted or unsubstituted alkyl,alkenyl, aryl or aralkyl group or a group selected from a halogen atom,—NO₂, —O—R_(d), —CO—R_(d), —CO—O—R_(d), —O—CO—R_(d), —CO—NR_(d)R_(e),—NR_(d)R_(e), —NR_(d)—CO—R_(e), —NR_(d)—CO—O—R_(e),—NR_(d)—CO—NR_(e)R_(f), —SR_(d), —SO—R_(d), —SO₂—R_(d), —SO₂—O—R_(d),—SO₂NR_(d)R_(e) or a perfluoroalkyl group. R_(d), R_(e) and R_(f)independently represent a hydrogen or a substituted or unsubstitutedalkyl, alkenyl, aryl or aralkyl group. The numbers of monomer units ncan be any integer from 5 to 200. The Y group can be a bond, (CH₂)_(q),or O(CH₂)_(q), wherein q is any integer from 1 to 100.

According to this pathway, a pentaerythritol polyethylene glycolderivative (9) reacts with toluenesulfonyl chloride to give acorresponding tosylate (10). The tosylate (10) is treated with sodiumazide to give the corresponding azide (11). This azide (11) ishydrogenated to give a tetraamine (12). The tetraamine then reacts withan aniline acid chloride (2) to give the desired polymeric aminesynergist having four aniline moieties. Lines leading to the center ofaromatic rings in the aniline acid (1), aniline acid chloride (2), andthe final polymeric amine synergist signify that the group can beattached at any available location on the ring.

Formula 11 illustrates a detailed synthetic pathway for one example of apolymeric amine synergist in accordance with the present disclosure:

According to this pathway, 4-dimethylaminobenzoic acid (13) is reactedwith thionyl chloride to give a corresponding acid chloride (14). Thisacid chloride (14) is reacted with a polyethyleneoxy polypropyleneoxyamine (15) to give the desired polymeric amine synergist (16).

A detailed synthetic pathway for another example of a polymeric aminesynergist in accordance with the present disclosure is shown in Formula12:

In this pathway, 4-dimethylaminobenzoic acid (13) reacts with thionylchloride to give a corresponding acid chloride (14). This acid chloride(14) is reacted with a polyethyleneoxy polypropyleneoxy diamine (17) togive the desired polymeric amine synergist (18) having two anilinemoieties.

The present disclosure also extends to photo curable inks, such as UVcurable inks including LED curable inks. In some examples, a photocurable ink can include a photo reactive binder (such as a UV curable orLED curable binder), a type-II photo initiator, a polymeric aminesynergist, a colorant, a co-solvent, and water. The polymeric aminesynergist can be an aminobenzene modified with a polyether chainconnecting to the aminobenzene through an amide linkage.

In some cases, the photo reactive binder can include a UV or LED curablepolyurethane and hydrophobic radiation-curable monomers. In one example,the photo reactive binder can include a waterdispersible (meth)acrylatedpolyurethane, such as NeoRad® R-441 by NeoResins (Avecia). Otherexamples of UV reactive binders can include Ucecoat® 7710, Ucecoat® 7655(available from Cytec), Neorad® R-440, Neorad® R-441, Neorad® R-447,Neorad® R-448 (available from DSM NeoResins), Bayhydrol® UV 2317,Bayhydrol® UV VP LS 2348 (available from Bayer), Lux 430, Lux 399, Lux484 (available from Alberdingk Boley), Laromer® LR 8949, Laromer® LR8983, Laromer® PE 22WN, Laromer® PE 55WN, or Laromer® UA 9060 (availablefrom BASF).

The polymeric amine synergists of the present disclosure can be usedtogether with a type-II photo initiator. The combination of type-IIphoto initiator with the polymeric amine synergist can interact byhydrogen abstraction. In this interaction, UV radiation causes ahydrogen radical to be abstracted from the polymeric amine synergistonto the type-II photo initiator. This creates two molecules havingradicals that can initiate polymerization in the photo reactive binder.

In some cases, the photo curable ink can include two different photoinitiators, or a photo initiator and a sensitizer. Some examples of typeII photo initiators can also act as sensitizers. In one example, thephoto curable ink can include a polymeric photo initiator that includesa xanthone analog, such as thioxanthone, connected to a polyether chain.In two more specific examples, the xanthone analog can connect to thepolyether chain through an ether linkage or an amide linkage. Thesetypes of photo initiators can act either as a type-II photo initiator oras a sensitizer. The photo curable ink can also include other polymericor non-polymeric photo initiators. Examples of radical photo initiatorsinclude, by way of illustration and not limitation,1-hydroxy-cyclohexylphenylketone, benzophenone,2,4,6-trimethylbenzo-phenone, 4-methylbenzophenone,diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, phenylbis(2,4,6trimethylbenzoyl) phosphine oxide,2-hydroxy-2-methyl-1-phenyl-1-propanone, benzyl-dimethyl ketal,2-methyl-I-[4-(methylthio)phenyl]-2-morpholinopropan-I-one, orcombinations thereof. Non-limiting examples of additional photoinitiators include alpha amino ketone UV photo initiators such as Ciba®Irgacure® 907, Ciba® Irgacure® 369, and Ciba® Irgacure® 379; bisacylphosphine oxide (BAPO) UV photo initiators such as Irgacure® 819,Darocur® 4265, and Darocur® TPO; alpha hydroxy ketone UV photoinitiators such as Irgacure® 184 and Darocur® 1173; including photoinitiators with or without sensitizers such as Darocur® ITX (2-isopropylthioxanthone).

The colorant in the photo curable ink can be a pigment, a dye, or acombination thereof. In some examples, the colorant can be present in anamount from 0.5 wt % to 10 wt % in the photo curable ink. In oneexample, the colorant can be present in an amount from 1 wt % to 5 wt %.In another example, the colorant can be present in an amount from 5 wt %to 10 wt %.

In some examples, the colorant can be a dye. The dye can be nonionic,cationic, anionic, or a mixture of nonionic, cationic, and/or anionicdyes. Specific examples of dyes that can be used include, but are notlimited to, Sulforhodamine B, Acid Blue 113, Acid Blue 29, Acid Red 4,Rose Bengal, Acid Yellow 17, Acid Yellow 29, Acid Yellow 42, AcridineYellow G, Acid Yellow 23, Acid Blue 9, Nitro Blue Tetrazolium ChlorideMonohydrate or Nitro BT, Rhodamine 6G, Rhodamine 123, Rhodamine B,Rhodamine B Isocyanate, Safranine O, Azure B, and Azure B Eosinate,which are available from Sigma-Aldrich Chemical Company (St. Louis,Mo.). Examples of anionic, water-soluble dyes include, but are notlimited to, Direct Yellow 132, Direct Blue 199, Magenta 377 (availablefrom Ilford AG, Switzerland), alone or together with Acid Red 52.Examples of water-insoluble dyes include azo, xanthene, methine,polymethine, and anthraquinone dyes. Specific examples ofwater-insoluble dyes include Orasol® Blue GN, Orasol® Pink, and Orasol®Yellow dyes available from Ciba-Geigy Corp. Black dyes may include, butare not limited to, Direct Black 154, Direct Black 168, Fast Black 2,Direct Black 171, Direct Black 19, Acid Black 1, Acid Black 191, MobayBlack SP, and Acid Black 2.

In other examples, the colorant can be a pigment. The pigment can beself-dispersed with a polymer, oligomer, or small molecule; or can bedispersed with a separate dispersant. Suitable pigments include, but arenot limited to, the following pigments available from BASF: Paliogen®Orange, Heliogen® Blue L 6901F, Heliogen® Blue NBD 7010, Heliogen® BlueK 7090, Heliogen® Blue L 7101F, Paliogen® Blue L 6470, Heliogen® Green K8683, and Heliogen® Green L 9140. The following black pigments areavailable from Cabot: Monarch® 1400, Monarch® 1300, Monarch® 1100,Monarch® 1000, Monarch® 900, Monarch® 880, Monarch® 800, and Monarch®700. The following pigments are available from CIBA: Chromophtal® Yellow3G, Chromophtal® Yellow GR, Chromophtal® Yellow 8G, Igrazin® Yellow 5GT,Igralite® Rubine 4BL, Monastral® Magenta, Monastral® Scarlet, Monastral®Violet R, Monastral® Red B, and Monastral® Violet Maroon B. Thefollowing pigments are available from Degussa: Printex® U, Printex® V,Printex® 140U, Printex® 140V, Color Black FW 200, Color Black FW 2,Color Black FW 2V, Color Black FW 1, Color Black FW 18, Color Black S160, Color Black S 170, Special Black 6, Special Black 5, Special Black4A, and Special Black 4. The following pigment is available from DuPont:Tipure® R-101. The following pigments are available from Heubach:Dalamar® Yellow YT-858-D and Heucophthal Blue G XBT-583D. The followingpigments are available from Clariant: Permanent Yellow GR, PermanentYellow G, Permanent Yellow DHG, Permanent Yellow NCG-71, PermanentYellow GG, Hansa Yellow RA, Hansa Brilliant Yellow 5GX-02, HansaYellow-X, Novoperm® Yellow HR, Novoperm® Yellow FGL, Hansa BrilliantYellow 10GX, Permanent Yellow G3R-01, Hostaperm® Yellow H4G, Hostaperm®Yellow H3G, Hostaperm® Orange GR, Hostaperm® Scarlet GO, and PermanentRubine F6B. The following pigments are available from Mobay: Quindo®Magenta, Indofast® Brilliant Scarlet, Quindo® Red R6700, Quindo® RedR6713, and Indofast® Violet. The following pigments are available fromSun Chemical: L74-1357 Yellow, L75-1331 Yellow, and L75-2577 Yellow. Thefollowing pigments are available from Columbian: Raven® 7000, Raven®5750, Raven® 5250, Raven® 5000, and Raven® 3500. The following pigmentis available from Sun Chemical: LHD9303 Black. Any other pigment and/ordye can be used that is useful in modifying the color of the UV curableink. Additionally, the colorant can include a white pigment such astitanium dioxide, or other inorganic pigments such as zinc oxide andiron oxide.

The components of the photo curable ink can be selected to give the inkgood ink jetting performance. Besides the photo curable binder,polymeric amine synergist, photo initiators, and the colorant, the photocurable ink can also include a liquid vehicle. Liquid vehicleformulations that can be used in the photo curable ink can include waterand one or more co-solvents present in total at from 1 wt % to 50 wt %,depending on the jetting architecture. Further, one or more non-ionic,cationic, and/or anionic surfactant can be present, ranging from 0.01 wt% to 20 wt %. In one example, the surfactant can be present in an amountfrom 5 wt % to 20 wt %. The liquid vehicle can also include dispersantsin an amount from 5 wt % to 20 wt %. The balance of the formulation canbe purified water, or other vehicle components such as biocides,viscosity modifiers, materials for pH adjustment, sequestering agents,preservatives, and the like. In one example, the liquid vehicle can bepredominantly water.

Classes of co-solvents that can be used can include organic co-solventsincluding aliphatic alcohols, aromatic alcohols, diols, glycol ethers,polyglycol ethers, caprolactams, formamides, acetamides, and long chainalcohols. Examples of such compounds include primary aliphatic alcohols,secondary aliphatic alcohols, 1,2-alcohols, 1,3-alcohols, 1,5-alcohols,ethylene glycol alkyl ethers, propylene glycol alkyl ethers, higherhomologs (C₆-C₁₂) of polyethylene glycol alkyl ethers, N-alkylcaprolactams, unsubstituted caprolactams, both substituted andunsubstituted formamides, both substituted and unsubstituted acetamides,and the like. Specific examples of solvents that can be used include,but are not limited to, 2-pyrrolidinone, N-methylpyrrolidone,2-hydroxyethyl-2-pyrrolidone, 2-methyl-1,3-propanediol, tetraethyleneglycol, 1,6-hexanediol, 1,5-hexanediol and 1,5-pentanediol.

One or more surfactants can also be used, such as alkyl polyethyleneoxides, alkyl phenyl polyethylene oxides, polyethylene oxide blockcopolymers, acetylenic polyethylene oxides, polyethylene oxide(di)esters, polyethylene oxide amines, protonated polyethylene oxideamines, protonated polyethylene oxide amides, dimethicone copolyols,substituted amine oxides, and the like. The amount of surfactant addedto the formulation of this disclosure may range from 0.01 wt % to 20 wt%. Suitable surfactants can include, but are not limited to, liponicesters such as Tergitol™ 15-S-12, Tergitol™ 15-S-7 available from DowChemical Company, LEG-1 and LEG-7; Triton™ X-100; Triton™ X-405available from Dow Chemical Company; LEG-1, and sodium dodecylsulfate.

Consistent with the formulation of this disclosure, various otheradditives can be employed to optimize the properties of the inkcomposition for specific applications. Examples of these additives arethose added to inhibit the growth of harmful microorganisms. Theseadditives may be biocides, fungicides, and other microbial agents, whichare routinely used in ink formulations. Examples of suitable microbialagents include, but are not limited to, NUOSEPT® (Nudex, Inc.),UCARCIDE™ (Union carbide Corp.), VANCIDE® (R.T. Vanderbilt Co.), PROXEL®(ICI America), and combinations thereof.

Sequestering agents, such as EDTA (ethylene diamine tetra acetic acid),may be included to eliminate the deleterious effects of heavy metalimpurities, and buffer solutions may be used to control the pH of theink. From 0.01 wt % to 2 wt %, for example, can be used. Viscositymodifiers and buffers may also be present, as well as other additives tomodify properties of the ink as desired. Such additives can be presentat from 0.01 wt % to 20 wt %.

Table 1 shows the composition of an example of a photo curable inkformulation (e.g. UV LED curable) in accordance with the presentdisclosure. The ink can be formulated by mixing these ingredients or byother formulations. The pH of the ink can then be adjusted. In oneexample, the ingredients can be stirred for 30 minutes, and then aqueouspotassium hydroxide can be added to adjust the pH to 8.5. It is notedthat though water concentrations are listed as “balance,” it isunderstood that the balance of components could included other liquidvehicle components or minor amounts of solids often present in inkjetink compositions.

TABLE 1 Component Weight Percent Photo reactive binder  1-20% Type-IIPhoto initiator 0.15-5% Co-photo initiator  0-10% Polymeric aminesynergist  0.1-5% Surfactant  0-10% Anti-kogation agent  0.1-5% Pigment0.5-10% Organic Co-solvent 0.1-50% Water remainder

The photo curable ink can be used to print on a broad selection ofsubstrates including untreated plastics, flexible as well as rigid,porous substrates such as paper, cardboard, foam board, textile, andothers. The ink has a good adhesion on a variety of substrates. Thephoto curable ink also has a good viscosity, enabling good printingperformances and enables the ability to formulate inks suitable forinkjet application. In some examples, the ink can be formulated forthermal inkjet printing. The photo-curable ink composition of thepresent disclosure enables high printing speed and is very well suitedfor a use in digital inkjet printing.

The polymeric amine synergists of the present disclosure can be stablein aqueous environments at pH from 7 to 12 or higher. Thus, the photocurable ink can be formulated to have a pH from 7 to 12 or higher. Insome examples, the photo curable ink can have a pH of 8 or higher. Inone specific example, the photo curable ink can have a pH of 8.5.

The polymeric amine synergist can exhibit less migration in cured inkcompared with small molecule synergists. The photo curable binder in theink can include polymers or monomers that polymerize or cross-linkduring the curing process. As the binder cures, the polymeric aminesynergist can become locked into the cured binder due to the longpolyether chain of the polymeric amine synergist. Therefore, the photocurable ink can be formulated so that there is little or no migration ofthe polymeric amine synergist in the ink after curing.

The present disclosure also extends to a method of making a photocurable ink. In an example, a method can include a step of mixing areactive binder, a photo initiator, a polymeric amine synergistincluding an aminobenze modified with a polyether chain connecting tothe aminobenzene through an amide linkage, a colorant, and a liquidvehicle including co-solvent and water. The photo curable ink can be UVcurable, and in one specific example, UV LED curable. In one example,the method can also include adjusting the pH of the ink to be from 7 to12. In another example, the method can include adjusting the pH of theink to be 8 or higher.

It is to be understood that this disclosure is not limited to theparticular process steps and materials disclosed herein because suchprocess steps and materials may vary somewhat. It is also to beunderstood that the terminology used herein is used for the purpose ofdescribing particular examples only. The terms are not intended to belimiting because the scope of the present disclosure is intended to belimited only by the appended claims and equivalents thereof.

It is noted that, as used in this specification and the appended claims,the singular forms “a,” “an,” and “the” include plural referents unlessthe context clearly dictates otherwise.

As used herein, “UV curable” refers to compositions that can be cured byexposure to ultraviolet light from any UV source such as a mercury vaporlamp, UV LED source, or the like. Mercury vapor lamps emit highintensity light at wavelengths from 240 nm to 270 nm and 350 nm to 380nm. “LED curable” refers to compositions that can be cured byultraviolet light from an ultraviolet LED. Ultraviolet LEDs typicallyemit light at specific wavelengths. For example, ultraviolet LEDs areavailable at 365 nm and 395 nm wavelengths, among others. The term“photo curable” refers generally to compositions that can be cured byexposure to light from any wavelength suitable for the composition beingcured. Typically, the photo curable composition will be UV curable, andin some cases UV LED curable.

As used herein, “liquid vehicle” or “ink vehicle” refers to a liquidfluid in which colorant is placed to form an ink. A wide variety of inkvehicles may be used with the systems and methods of the presentdisclosure. Such ink vehicles may include a mixture of a variety ofdifferent agents, including, surfactants, solvents, co-solvents,anti-kogation agents, buffers, biocides, sequestering agents, viscositymodifiers, surface-active agents, water, etc.

As used herein, “colorant” can include dyes and/or pigments.

As used herein, “dye” refers to compounds or molecules that absorbelectromagnetic radiation or certain wavelengths thereof. Dyes canimpart a visible color to an ink if the dyes absorb wavelengths in thevisible spectrum.

As used herein, “pigment” generally includes pigment colorants, magneticparticles, aluminas, silicas, and/or other ceramics, organo-metallics orother opaque particles, whether or not such particulates impart color.Thus, though the present description primarily exemplifies the use ofpigment colorants, the term “pigment” can be used more generally todescribe not only pigment colorants, but other pigments such asorganometallics, ferrites, ceramics, etc. In one specific example,however, the pigment is a pigment colorant.

As used herein, “ink-jetting” or “jetting” refers to compositions thatare ejected from jetting architecture, such as ink-jet architecture.Ink-jet architecture can include thermal or piezo architecture.Additionally, such architecture can be configured to print varying dropsizes such as less than 10 picoliters, less than 20 picoliters, lessthan 30 picoliters, less than 40 picoliters, less than 50 picoliters,etc.

As used herein, the term “substantial” or “substantially” when used inreference to a quantity or amount of a material, or a specificcharacteristic thereof, refers to an amount that is sufficient toprovide an effect that the material or characteristic was intended toprovide. The exact degree of deviation allowable may in some casesdepend on the specific context.

As used herein, the term “about” is used to provide flexibility to anumerical range endpoint by providing that a given value may be “alittle above” or “a little below” the endpoint. The degree offlexibility of this term can be dictated by the particular variable anddetermined based on the associated description herein.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary.

Concentrations, amounts, and other numerical data may be expressed orpresented herein in a range format. It is to be understood that such arange format is used merely for convenience and brevity and thus shouldbe interpreted flexibly to include not only the numerical valuesexplicitly recited as the limits of the range, but also to includeindividual numerical values or sub-ranges encompassed within that rangeas if each numerical value and sub-range is explicitly recited. As anillustration, a numerical range of “about 1 wt % to about 5 wt %” shouldbe interpreted to include not only the explicitly recited values ofabout 1 wt % to about 5 wt %, but also include individual values andsub-ranges within the indicated range. Thus, included in this numericalrange are individual values such as 2, 3.5, and 4 and sub-ranges such asfrom 1-3, from 2-4, and from 3-5, etc. This same principle applies toranges reciting only one numerical value. Furthermore, such aninterpretation should apply regardless of the breadth of the range orthe characteristics being described.

EXAMPLES

The following illustrates several examples of the present disclosure.However, it is to be understood that the following are only illustrativeof the application of the principles of the present disclosure. Numerousmodifications and alternative compositions, methods, and systems may bedevised without departing from the spirit and scope of the presentdisclosure. The appended claims are intended to cover such modificationsand arrangements.

Example 1

Synthesis of 4-dimethylaminobenzoic acid chloride: To a mixture of4-dimethylaminobenzoic acid (50 g, 0.303 mol) in 550 mL of THF was addeda solution of thionyl chloride (72 g, 45 mL, 0.605 mol) in 50 mL of THF.The resulting mixture was heated to reflux for 24 hours. After coolingdown to room temperature, THF and unreacted thionyl chloride wereevaporated off by vacuum, giving rise to the desired4-dimethylaminobenzoic acid chloride (56 g, 100% yield). The materialwas used for next step reaction without further purification.

Example 2

Synthesis of bis-(4-dimethylaminobenzoic acid) derivative of Jaffamine®ED-900: A mixture of 4-dimethylaminobenzoic acid chloride (27.8 g,0.1515 mol), Jeffamine® ED-900 (68.2 g, 0.075 mol) and triethylamine (16g, 0.1515 mol) in 200 mL of THF and 125 ml of chloroform was refluxedfor 24 hours. Then the solid was filtered off, the mother filtrate wasevaporated off to give a residue. The residue was purified by columnflash chromatography to give the desired bis-(4-dimethylaminobenzoicacid) derivative of Jeffamine® ED-900 (70 g, 78% yield).

Example 3

Synthesis of mono-(4-dimethylaminobenzoic acid) derivative of Jeffamine®M-1000: A mixture of 4-dimethylaminobenzoic acid chloride (20 g, 0.108mol), Jeffamine® M-1000 (108 g, 0.108 mol) and triethylamine (12 g,0.118 mol) in 200 mL of THF and 125 mL of chloroform was refluxed for 24hours. Then the solid was filtered off, the mother filtrate wasevaporated off to give a residue. The residue was purified by columnflash chromatography to give the desired mono-(4-dimethylaminobenzoicacid) derivative of Jeffamine® M-1000 (65 g, 52% yield).

Example 4

A photo (UV LED) curable inkjet ink is prepared by mixing the followingcomponents as shown in Table 2.

TABLE 2 Component Weight Percent UV reactive binder  15% Irgacure ® 819(co-photo initiator) 0.3% Thioxanthone derivative of PEG-600 0.5%(type-II photo initiator) bis-(4-dimethylaminobenzoic acid) 0.5%derivative of Jaffamine ® ED-900 (polymeric amine synergist) LEG-1(surfactant)  1% CT-211 (surfactant)  1% Crodafos ® N3 (anti-kogationagent) 0.5% Pigments 2.5% 2-hydroxyethyl-2-pyrrolidone  10% (co-solvent)Water 69.2% 

Example 5

A photo (UV LED) curable inkjet ink is prepared by mixing the followingcomponents as shown in Table 3.

TABLE 3 Component Weight Percent UV reactive binder  15% Irgacure ® 819(co-photo initiator) 0.3% Thioxanthone derivative of PEG-600 0.5%(type-II photo initiator) mono-(4-dimethylaminobenzoic acid) 0.5%derivative of Jeffamine ® M-1000 (polymeric amine synergist) LEG-1(surfactant)  1% CT-211 (surfactant)  1% Crodafos ® N3 (anti-kogationagent) 0.5% Pigments 2.5% 2-hydroxyethyl-2-pyrrolidone  10% (co-solvent)Water 69.2% 

Example 6

A photo curable inkjet ink is prepared by mixing the followingcomponents as shown in Table 4.

TABLE 4 Component Weight Percent UV reactive binder  5% Thioxanthonederivative of PEG-600 0.25%  (type-II photo initiator)bis-(4-dimethylaminobenzoic acid) 0.5% derivative of Jaffamine ® ED-900(polymeric amine synergist) LEG-1 (surfactant)  1% CT-211(surfactant)0.5% Crodafos ® N3 0.5% (anti-kogation agent) Pigments  3%2-hydroxyethyl-2-pyrrolidone  10% (co-solvent) Water 79.15% 

Example 7

A photo curable inkjet ink is prepared by mixing the followingcomponents as shown in Table 5.

TABLE 5 Component Weight Percent UV reactive binder  10% Thioxanthonederivative of PEG-600 0.25%  (type-II photo initiator)bis-(4-dimethylaminobenzoic acid) 0.5% derivative of Jaffamine ® ED-900(polymeric amine synergist) LEG-1 (surfactant)  1% CT-211(surfactant)0.5% Crodafos ® N3 0.5% (anti-kogation agent) Pigments  3%2-hydroxyethyl-2-pyrrolidone  10% (co-solvent) Water 74.15% 

Example 8

A photo (UV LED) curable inkjet ink is prepared by mixing the followingcomponents as shown in Table 6.

TABLE 6 Component Weight Percent UV reactive binder  15% Irgacure ® 819(co-photo initiator) 0.3% Thioxanthone derivative of PEG-600 0.5%(type-II photo initiator) bis-(4-dimethylaminobenzoic acid)  1%derivative of Jaffamine ® ED-900 (polymeric amine synergist) LEG-1(surfactant)  1% CT-211 (surfactant)  1% Crodafos ® N3 (anti-kogationagent) 0.5% Pigments 2.5% 2-hydroxyethyl-2-pyrrolidone  10% (co-solvent)Water 68.7% 

Example 9

A photo (UV LED) curable inkjet ink is prepared by mixing the followingcomponents as shown in Table 7.

TABLE 7 Component Weight Percent UV reactive binder  15% Irgacure ® 819(co-photo initiator) 0.3% Thioxanthone derivative of PEG-600 0.5%(type-II photo initiator) bis-(4-dimethylaminobenzoic acid)  3%derivative of Jaffamine ® ED-900 (polymeric amine synergist) LEG-1(surfactant)  1% CT-211 (surfactant)  1% Crodafos ® N3 (anti-kogationagent) 0.5% Pigments 2.5% 2-hydroxyethyl-2-pyrrolidone  10% (co-solvent)Water 66.7% 

Example 10

A photo (UV LED) curable inkjet ink is prepared by mixing the followingcomponents as shown in Table 8.

TABLE 8 Component Weight Percent UV reactive binder  15% Irgacure ® 819(co-photo initiator) 0.3% Thioxanthone derivative of PEG-600 0.5%(type-II photo initiator) bis-(4-dimethylaminobenzoic acid)  5%derivative of Jaffamine ® ED-900 (polymeric amine synergist) LEG-1(surfactant)  1% CT-211 (surfactant)  1% Crodafos ® N3 (anti-kogationagent) 0.5% Pigments 2.5% 2-hydroxyethyl-2-pyrrolidone  10% (co-solvent)Water 64.7% 

Example 11

A photo (UV LED) curable inkjet ink was prepared with the ingredientsand proportions as in Example 4, using the following method: (1) MixUV-curable polyurethane dispersion, 30% of the water amount and IRG819PI dispersion at 60° C. for 5 min; (2) Mix 2HE2P, 70% of the wateramount, Crodafos® N3A, CT211, and LEG-1, then neutralize to pH=7.5 withKOH solution; (3) Combine the mixtures from steps (1) and (2); (4) Addthioxanthone derivative of PEG-600 and bis-(4-dimethylaminobenzoic acid)derivative of Jaffamine® ED-900, mix well until they are dissolved intothe mixture; (5) Mix (4) Into 14-SE-73 pigment dispersion; and (6)Adjust to pH=8.5 using KOH solution.

Example 12

A print test of the ink from Example 11 was performed using thefollowing method: (1) Ink is filled into TIJ4 pen; (2) Fixer is printedfrom a different pen onto two paper substrates: offset coated paper(Sterling Ultra Gloss “SUG”) and whitetop coated Kraft liner RockTenn 1(“RT1”); (3) The ink is printed onto the paper substrates; (4) The inkis immediately dried using hot air blower for 5 seconds at 375° F.; and(5) The dried ink is then immediately cured at a speed of 100 fpm usinga 16 W/cm² LED 395 nm wavelength (from Phoseon).

Example 13

Durability tests were performed on the printed ink from Example 12. Awet rub test was performed after a pre-defined time period afterprinting and curing. For SUG, the wet rub test was performed 24 hr afterprinting. For RT1, the test was preformed 72 hrs after printing. A Tabertest tool was used with Crockmeier cloth attached to the tip. The weightload was 350 g. One cycle was performed for SUG, two cycles for RT1.Windex® solution was used during the wet rub test. The delta opticaldensity (OD) was measured before and after the rub. The lower the ΔOD,the better the durability. A ΔOD<0.15 is considered a very good score.An immediate dry rub test was also performed. In this test, a hand heldrubbing tool was used to assess the smearing of dried and cured inkimmediately after printing. The tool was fit with a rubber tip that whenpushed down applies a constant pressure of 6-7 lb. The OD was measuredbefore and after the rub to obtain a ΔOD or change in optical density.The lower the ΔOD, the better the durability. A ΔOD<0.15 is considered avery good score. The results of the tests were as follows: The Example 4black ink was printed as described above in two methods: Test 1—with thecuring step; Test 2—without the curing step. The durability was testedon both papers, SUG and RT1, using both durability methods describedabove, namely, Wet Rub and Immediate Dry Rub. The results are shown inTable 9:

TABLE 9 Test 1 - with Test 2 - without Example 4 Curing ΔOD Curing ΔODBlack Ink Wet Immediate Wet Immediate on Media Rub Dry Rub Rub Dry RubSUG 0.23 0.14 1.73 0.71 RT1 0.13 0.06 1.24 0.5

The results show that Example 4 black ink had significantly better wetrub and immediate dry rub resistance after curing. Initial OD was 2.08and 1.76 on SUG and RT1 respectively; therefore a ΔOD of 0.23, forexample, means that after rubbing the print lost 0.23 OD units out ofthe initial 2.08 OD measuring, a ΔOD of 1.73 means that that inksignificantly lost 1.73 OD units out of the initial 2.08 OD measurement.The durability improvement by curing is evident in both Wet Rub andImmediate Dry Rub measurements suggesting that the thioxanthonesensitizer and polymeric amine synergist package are efficiently curingand crosslinking the ink.

While the present technology has been described with reference tocertain examples, those skilled in the art will appreciate that variousmodifications, changes, omissions, and substitutions can be made withoutdeparting from the spirit of the disclosure. It is intended, therefore,that the disclosure be limited only by the scope of the followingclaims.

What is claimed is:
 1. A polymeric amine synergist having formula:

wherein m, n, and p are independently any integer provided that the sumof m, n, and p is from 10 to 25 and that m or p is at least 1, andwherein the polymeric amine synergist has a molecular weight from about500 Mw to about 5000 Mw.
 2. The polymeric amine synergist of claim 1,wherein the polymeric amine synergist is stable in water at a pH from 7to
 12. 3. The polymeric amine synergist of claim 1, wherein thepolyether chain is derived from a polyethyleneoxy polypropyleneoxy chainportion of a polyethyleneoxy polypropyleneoxy amine.
 4. The polymericamine synergist of claim 1, wherein the polymeric amine synergist has awater solubility of at least 0.5 wt%.
 5. A photo curable ink,comprising: a photo reactive binder; a polymeric amine synergistcomprising an aminobenzene modified with a polyether chain connecting tothe aminobenzene through an amide linkage such that the polyether chainis directly bonded to a nitrogen atom of the amide group, wherein thepolyether chain comprises a copolymer of polyethylene glycol andpolypropylene glycol; a type-II photo initiator; a colorant; and aliquid vehicle including co-solvent and water.
 6. The photo curable inkof claim 5, wherein the photo curable ink has a pH from 7 to 12 and thepolymeric amine synergist is stable in the photo curable ink.
 7. Thephoto curable ink of claim 5, wherein the polymeric amine synergist doesnot migrate in the photo curable ink after curing.
 8. The photo curableink of claim 5, wherein the type-II photo initiator is a polymeric photoinitiator and wherein the photo curable ink further comprises a co-photoinitiator.
 9. A method of making a photo curable ink, comprising mixinga photo reactive binder, a polymeric amine synergist comprising anaminobenzene modified with a polyether chain connecting to theaminobenzene through an amide linkage such that the polyether chain isdirectly bonded to a nitrogen atom of the amide group, wherein thepolyether chain comprises a copolymer of polyethylene glycol andpolypropylene glycol, a type-II photo initiator, a colorant, and aliquid vehicle including co-solvent and water.
 10. The polymeric aminesynergist of claim 1, wherein n is an integer from 9 to 15 and m+p isfrom 4 to
 8. 11. The photo curable ink of claim 5, wherein the photocurable ink has a pH of 8 or higher.
 12. The photocurable ink of claim5, wherein the polymeric amine synergist has a molecular weight fromabout 500 Mw to about 5000 Mw.
 13. The photocurable ink of claim 5,wherein the polyether chain is derived from a polyethyleneoxypolypropyleneoxy chain portion of a polyethyleneoxy polypropyleneoxyamine.